Method to improve inductance with a high-permeability slotted plate core in an integrated circuit

ABSTRACT

An inductor structure ( 102 ) formed in an integrated circuit ( 100 ) is disclosed, and includes a first isolation layer ( 106 ) and a first core plate ( 104 ) disposed over or within the first isolation layer ( 106, 114 ). The first core plate ( 104 ) includes a plurality of electrically coupled conductive traces composed of a conductive ferromagnetic material layer. A second isolation layer ( 108 ) overlies the first isolation layer and an inductor coil ( 102 ) composed of a conductive material layer ( 118 ) is formed within the second isolation layer ( 108 ). Another core plate may be formed over the coil. The one or more core plates increase an inductance (L) of the inductor coil ( 102 ).

FIELD OF INVENTION

The present invention relates generally to semiconductor devices andmore particularly to an improved inductor formed together with one ormore high permeability conductive core plates suitable for use as aplate of a planar capacitor in the fabrication of integrated circuitdevices.

BACKGROUND OF THE INVENTION

In the manufacture of semiconductor products such as integratedcircuits, individual electrical devices are formed on or in asemiconductor substrate, and are thereafter interconnected to formcircuits. Interconnection of these devices within an integrated circuitis typically accomplished by forming a multi-level interconnect networkin layers formed over the electrical devices, by which the device activeelements are connected to other devices to create the desired circuits.Individual wiring layers within the multi-level network are formed bydepositing an insulating or dielectric material layer such as SiO₂ overthe discrete devices or over a previous interconnect layer, andpatterning and etching contact openings such as vias. A second patternand etch defines trenches, the wiring between vias. Conductive material,such as copper is then deposited into the vias and trenches andplanarized to form the next level of interconnect. Dielectric orinsulating material then deposited over the patterned conductive layer,and the process may be repeated any number of times using additionalwiring levels laid out over additional dielectric layers with conductivevias therebetween to form the multi-level interconnect network.

Integrated circuits used in radio frequency (RF) applications maycontain inductors and capacitors in addition to the common use oftransistors, diodes and resistors. Such integrated inductors andcapacitors may be formed in the multi-level networks of the interconnectlayers.

As device densities and operational speeds continue to increase anddevice scaling proceeds into the deep sub-micron regime, reduction ofinductor and capacitor sizes in integrated circuits is also highlydesired as these devices may require significant area within anintegrated circuit to achieve the desired inductance (L) or capacitance(C). In addition, the location and structure of such passive devices maybe particularly sensitive to stray capacitive coupling and noise,particularly when used as components of high input impedance or highgain circuits, high speed switching circuits, or RF integrated circuits.

Some prior art integrated inductor or capacitor designs use anassociated solid conductive plate or shield layer. Such solid conductivelayers may tend to develop eddy currents within the plates thatneedlessly consume power and degrade the efficiency of the device.

Accordingly, it is desirable to fabricate an improved inductorintegrated within a semiconductor device.

SUMMARY OF THE INVENTION

The following presents a simplified summary in order to provide a basicunderstanding of one or more aspects of the invention. This summary isnot an extensive overview of the invention, and is neither intended toidentify key or critical elements of the invention, nor to delineate thescope thereof. Rather, the primary purpose of the summary is to presentsome concepts of the invention in a simplified form as a prelude to themore detailed description that is presented later.

The present invention relates to an improved inductor structure having ahigh-permeability core plate material (e.g., cobalt, nickel, tantalum, aTiN/Co/TiN stack, a TaN/Co stack, or another high-permeabilityferromagnetic core material) associated therewith that may double as acapacitor plate integrated within a semiconductor device during thefabrication of integrated circuit devices. The device of the presentinvention effectively improves inductance by using one or morehigh-permeability ferromagnetic material core plates in close proximityto the inductor coil. The inductor further mitigates eddy currentswithin the core plate by use of slotted or spaced apart traces in eachplate. Capacitive coupling with adjacent circuit elements orinterconnects and a variety of noise sources are further reduced oravoided by the use of these conductive core plates.

In one aspect of the present invention, the inductor comprises aninductor coil formed of a conductive material (e.g., copper, aluminum,tantalum, or a TaN/Al stack) in a trench within an insulative layer(e.g., TaN, SiO2, an etch-stop material, SiN, SiC, SiC:H, or anotherinsulative or dielectric material) along with, or adjacent to thehigh-permeability core plate layer.

In another aspect of the invention, the isolation layers between theconductive portions of the inductor structure comprise one of an OSG,FSG, TEOS, a low-k dielectric material, or an ultra low-k dielectricmaterial. In one or more aspects of the invention, the inductorstructure may be fabricated, for example, between one or moremulti-level interconnect metal layers of a semiconductor device, abovethe metal layers, or within one or more of the protective overcoat(e.g., PO, PO2) layers.

In another preferred aspect of the present invention, since theferromagnetic core plate material comprises a conductor, the plate mayalso be utilized as one plate of a capacitor associated with theintegrated circuit. In another aspect, the capacitor plate/core platemay be electrically connected in series with the inductor coil to form aseries L-C circuit, or alternately, may be wired separately.

In yet another preferred aspect of the invention, the conductiveferromagnetic core plate comprises slotted or spaced apart traces whenformed in a planar configuration to mitigate eddy current losses, and tolimit power consumption in the device. Alternately, the inductor coilmay be formed in the trench overlying a layer of the high-permeabilitycore material and etched, for example, to form spaces or slots betweenthe turns of the coil. In this way, eddy currents are still avoidedwhile the inductor coil and the core plate structures remainelectrically continuous along the length of the coil.

In still another aspect of the present invention, the conductive coreplate(s) provide a shield to the inductor to sufficiently shield thedevice from noise to provide more predictable inductor performance.

In a method aspect of the present invention, the inductor structure maybe formed, for example, overlying a semiconductor substrate, and a firstisolation layer (e.g., TaN, SiO2, an etch-stop material, SiN, SiC,SiC:H, or another insulative or dielectric material) disposedtherebetween. Trenches are then formed within the first isolation layer,a core plate comprising a conductive ferromagnetic material layer (e.g.,cobalt, nickel, tantalum, a TiN/Co/TiN stack, a TaN/Co stack, or anotherhigh-permeability ferromagnetic core material) is then disposed withinthe trenches, followed by a second isolation layer over the core plate.An inductor coil comprising a conductive material layer (e.g., copper,aluminum, tantalum, or a TaN/Al stack) is then disposed within thetrenches associated with the second isolation layer and overlying thecore plate. A portion of the conductive material layer, the core plate,and isolation layers is removed to pattern the turns of the inductorcoil and provide isolation spaces between the electrically conductiveturns of the inductor coil and the ferromagnetic core plate layer.Optionally, a third isolation layer or protective overcoat layer (e.g.,PO, PO2) may be added overlying the inductor coil and the core plate.

The first and third isolation layers (e.g., an OSG, FSG, TEOS, a low-kdielectric material, or an ultra low-k insulative materials) aredisposed above and below the inductor to electrically isolate theinductor between, for example, the interconnect metal layers, ILD, IMD,or PO, or PO2 layers.

In yet another aspect of the invention a second core plate may be formedoverlying the third isolation layer to provide additional inductancepermeability. In still another aspect of the invention, the traces ofthe first and second core plates of the inductor structure are alignedorthogonal to each other.

Electrical connections to the inductor structure are provided byconductive vias attached to the ends of the inductor coil extendingthrough respective openings in the isolation layers and through slots orother such openings in the core plates. Such slots in the shield layersalso mitigate eddy current losses in the core plates or capacitor platethat would otherwise develop in solid or continuous conductive layers.

Beneficially, the invention provides improved inductance and morepredictable integrated inductor performance while mitigating eddycurrents and utilizing a ferromagnetic material (e.g., cobalt) currentlyused in most standard semiconductor processes.

To the accomplishment of the foregoing and related ends, the followingdescription and annexed drawings set forth in detail certainillustrative aspects and implementations of the invention. These areindicative of but a few of the various ways in which the principles ofthe invention may be employed. Other aspects, advantages and novelfeatures of the invention will become apparent from the followingdetailed description of the invention when considered in conjunctionwith the drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1A is a top view illustrating an exemplary integrated inductorstructure having a single turn coil disposed within isolation layers ofa semiconductor device in accordance with an aspect of the presentinvention;

FIG. 1B is a cross-sectional side view taken along section line AA ofFIG. 1A, illustrating an exemplary integrated inductor structure of thesingle turn coil and a ferromagnetic material core plate disposed belowthe inductor coil within isolation layers of the semiconductor device ofFIG. 1A;

FIG. 2A is a simplified top view illustrating an exemplary integratedinductor structure having a two turn coil disposed within isolationlayers of a semiconductor device in accordance with an aspect of thepresent invention;

FIG. 2B is a cross-sectional side view taken along section line BB ofFIG. 2A, illustrating an exemplary integrated inductor structure of thetwo turn coil and a ferromagnetic material core plate disposed above andbelow the inductor coil within isolation layers of the semiconductordevice of FIG. 2A;

FIG. 3A is a simplified top view illustrating an exemplary integratedinductor structure having a two turn coil disposed within isolationlayers of a semiconductor device in accordance with an aspect of thepresent invention;

FIG. 3B is a cross-sectional side view taken along section line CC ofFIG. 3A, illustrating an exemplary integrated inductor structure of thetwo turn coil connected to a lower ferromagnetic material core plate andan upper core plate disposed within isolation layers of thesemiconductor device of FIG. 3A;

FIG. 4 is an exploded isometric view of an exemplary embodiment of thepresent invention illustrating an improved single turn inductorstructure disposed between two isolation layers disposed between twoconductive ferromagnetic core plates each core plate comprising aplurality of mutually electrically conductive spaced apart traces;

FIG. 5A is a simplified top view illustrating an exemplary integratedinductor structure having a two turn coil disposed within isolationlayers of a semiconductor device in accordance with an aspect of thepresent invention;

FIG. 5B is a cross-sectional side view taken along section line DD ofFIG. 5A, illustrating an exemplary integrated inductor structure of thetwo turn coil and an overlying ferromagnetic material core plate layerdisposed within a PO2 isolation layer of the semiconductor device ofFIG. 5A;

FIG. 6A is a simplified top view illustrating an exemplary integratedinductor structure having a two turn coil disposed within isolationlayers of a semiconductor device in accordance with an aspect of thepresent invention;

FIG. 6B is a cross-sectional side view taken along section line EE ofFIG. 6A, illustrating an exemplary integrated inductor structure of thetwo turn coil overlying a ferromagnetic material core plate layerdisposed together within a trench in the PO and PO2 isolation layers ofthe semiconductor device of FIG. 6A;

FIG. 7A is a simplified top view illustrating an exemplary integratedinductor structure having a two turn coil disposed within isolationlayers of a semiconductor device in accordance with an aspect of thepresent invention; and

FIG. 7B is a cross-sectional side view taken along section line FF ofFIG. 7A, illustrating an exemplary integrated inductor structure of thetwo turn coil overlying a ferromagnetic material core plate layerdisposed together within a trench in the top IMD isolation layers of thesemiconductor device of FIG. 7A.

DETAILED DESCRIPTION OF THE INVENTION

The present invention will now be described with reference to theattached drawings, wherein like reference numerals are used to refer tolike elements throughout. The invention relates to an integratedinductor structure formed together with, or in close proximity to aslotted high-permeability core plate during interconnect metal levelprocessing of integrated circuits and other devices. One or moreimplementations of the invention are hereinafter illustrated anddescribed in the context of the fabrication of the integrated inductorstructure and the core plate in semiconductor devices, utilizingferromagnetic material layers, etch-stop layers, isolation layers,tantalum, and other interconnect metal or conductive layers. However, itwill be appreciated by those skilled in the art, that the invention isnot limited to the exemplary implementations illustrated and describedhereinafter. In particular, a variety of such materials may be used toform the structures discussed.

As previously indicated, because of increasing device densities and therelatively large size of passive components such as inductors andcapacitors in integrated circuits, even incremental reductions in thesize of these devices is becoming increasingly desirable. The currentchallenge addressed in the present invention, is to fabricate higherinductance L and capacitance C devices in ever smaller dimensions. Tothis end, several methodologies are utilized in the context of thepresent invention.

As inductance L is proportional to permeability, one such approachincorporates positioning a conductive high-permeability core plate inclose proximity to the inductor coil to increase the inductance of thedevice. In one aspect of the invention, the core plate comprises ahigh-permeability ferromagnetic material (e.g., cobalt, nickel,tantalum, a TiN/Co/TiN stack, a TaN/Co stack, or anotherhigh-permeability ferromagnetic core material) that is conductive toprovide shielding and double as a capacitor plate, and slotted to avoideddy current losses. The present invention presents two suchimplementations of the core plate approach; a planar core plate placedclose to the inductor coil, and a contoured core plate layer formedtogether with and around the inductor coil. Each approach has certainadvantages as will be discussed hereinafter in connection with thefigures.

The present invention provides several other distinct benefits overprior art structures where space and size are important. The use of aconductive material for the core plate, whether in the form of a planarplate, or a contoured layer, offers more efficient space utilization byproviding at least one plate of a capacitor in the same space. Inanother variation of the implementation, if two such conductive coreplates are utilized, for example, one plate above and one below theinductor, a complete capacitor, or alternately, two plates of twoindependent capacitors would be provided. Other advantages of theconductive ferromagnetic core plate concept over that of a prior artinsulative ferromagnetic material layer, are that the conductive corematerial provides a higher permeability and a more effective shieldlayer to electromagnetic (EM) interference, various noise sources, andstray capacitive coupling.

A further advantage is offered by the approach of the present invention,wherein a ferromagnetic material (e.g., cobalt) currently used in somesemiconductor processes may be utilized. Thus, compared to the priorart, specialized materials or extra process steps are not required inthe fabrication of the integrated inductor structure in at least oneexample of the present invention. This is due, in part, because in oneexample, a process comprises cobalt for the silicide process, and copperand aluminum diffusion barriers formed between the metal and thedielectric layers as well as between the metal layers and the siliconsubstrate. Such barriers are typically formed using conductive compoundsof transition metals such as tantalum, tantalum nitride, tantalumsilicon nitride, PVD tantalum, titanium nitride, and tungsten nitride aswell as the various transition metals themselves. Insulators such assilicon nitride and silicon oxynitride have also been used as barriermaterials between copper metallurgy and insulative layers. Morerecently, silicon carbide (SiC) has been used as a copper diffusionbarrier material, as well an etch-stop layer and a hard mask used duringtrench and/or via cavity formation.

RC delay times associated with the metal interconnect layers may also beimproved by utilizing new porous low dielectric constant (low-k)dielectric materials formed between the wiring metal lines, in order toreduce the capacitance therebetween and consequently to increase circuitspeed. Examples of low-k dielectric materials include thespin-on-glasses (SOGs), as well as organic and quasi-organic materialssuch as polysilsesquioxanes, fluorinated silica glasses (FSGs) andfluorinated polyarylene ethers. Organic, non silicaceous materials suchas the fluorinated polyarylene ethers are seeing an increased usage insemiconductor processing technology because of their favorabledielectric characteristics and ease of application. Other low-kinsulator materials include organo-silicate-glasses (OSGs), and ultralow-k dielectrics. OSG materials, for example, may be low densitysilicate glasses to which alkyl groups have been added to achieve alow-k dielectric characteristic.

FIG. 1A, for example, illustrates a top view of an exemplary integratedinductor structure L having a single turn coil disposed within isolationlayers of a semiconductor device 100 in accordance with an aspect of thepresent invention.

FIG. 1B is a cross-sectional side view taken along section line AA ofFIG. 1A, illustrating the exemplary integrated inductor structure L ofthe semiconductor device 100 of FIG. 1A. In the semiconductor device100, the inductor structure L comprises the single turn coil 102 and aferromagnetic material core plate 104 disposed below the inductor coil102 within the isolation layers, for example, within interleveldielectric layer ILD 106 (a first isolation layer) and the topinter-metal dielectric layer top IMD 108 (a second isolation layer).

Preferably, the inductor structure L of device 100, for example, isformed above a semiconductor substrate in or above the copper metalinterconnect layers such as a copper Mx-1 layer 110, wherein the bondpads 110 for the inductor L and an unrelated via structure 112 areshown. An etch-stop layer 114 (e.g., TiN, SiC, SiC:N, or another etchstop material) may then be formed overlying the copper bond pads of theMx-1 interconnect layer 110, followed by the core plate 104 comprising aconductive ferromagnetic material layer (e.g., cobalt, nickel, tantalum,a TiN/Co/TiN stack, a TaN/Co stack, or another high-permeabilityferromagnetic core material). The ferromagnetic core plate layer 104, inone example, is patterned to form slots or other spaced apart traces inthe conductive plate, which are mutually electrically conductive to eachother to avoid eddy current losses in the plate.

Isolation layers ILD 106 and TOP IMD 108 formed over the core plate 104and the etch stop layer 114, may comprise insulating or dielectricmaterials (e.g., TaN, SiO₂, an etch-stop material, SiN, SiC, SiC:H, oranother insulating material). Trenches are then formed within theisolation layers 106 and 108 (e.g., consistent with a dual damasceneprocess), wherein a diffusion barrier layer 116 (e.g., TaN, TiN) and aconductive material layer 118 (e.g., copper, aluminum, tantalum, or aTaN/Al stack) is disposed within the trenches to form the inductor coil102. The structure may then receive a CMP operation for planarization tofurther define the shape and turns of the inductor coil 102 and toelectrically isolate the electrically conductive turns of the inductorcoil 102. Because etch stop layer 114 is also insulative, it may beconsidered a first isolation layer or a part of the first isolationlayer 106. In such case, the core plate 104 may be considered disposedover an upper surface of, or within, the first insulation layer.

Thus, an inductor coil comprising a conductive material is disposed andformed within the trenches of the second isolation layer 108 overlyingthe first isolation layer 106 and the core plate 104. Optionally, theformation of the inductor structure L may be followed by anotherdeposition of an etch-stop material layer 120 and one or more protectiveovercoat layers, for example, protective overcoat layer PO 122, andprotective overcoat layer PO2 124 (a third isolation layer) overlyingthe inductor coil 102 and the core plate 104.

Vias, such as 112 comprising additional diffusion barrier layers 126 andconductive interconnects 128 may be formed within the protectiveovercoat layers PO 122, and PO2 124 to interconnect to the underlyingcircuit elements and structures. Bond pads 130 may be then formedoverlying the via structures or other openings for electrical connectionto one or more terminals 134 of the inductor 102. In the exemplarydevice 100 of FIGS. 1A and 1B, one terminal 134 a of the inductor coil102 connects to the Mx-1 copper layer 110 under the inductor L, and theother terminal 134 b connects to a bond pad 130 above inductor L.

FIG. 2A illustrates a top view of an exemplary integrated inductorstructure L having a two turn coil disposed within isolation layers of asemiconductor device 200 in accordance with another aspect of thepresent invention.

FIG. 2B is a cross-sectional side view taken along section line BB ofFIG. 2A, illustrating the exemplary integrated inductor structure L ofthe semiconductor device 200 of FIG. 2A. The inductor structure L ofFIGS. 2A and 2B is similar to that of the inductor of FIGS. 1A and 1B,and as such need not be fully described again for the sake of brevityexcept where noted. In the semiconductor device 200, the inductorstructure L comprises the two turn coil 202 and a ferromagnetic materialcore plate 204 disposed above and below the inductor coil 202 within theisolation layers, for example, within interlevel dielectric layer ILD206 (a first isolation layer) and over a top inter-metal dielectriclayer TOP IMD 208 (a second isolation layer).

Again, the inductor structure L of device 200, for example, is formedabove a semiconductor substrate in or above the copper metalinterconnect layers such as a copper Mx-1 layer 210, wherein bond padsfor the inductor L and an unrelated via structure 212 are shown. Anetch-stop layer 214 (e.g., TiN, Sic, SiC:N, or another etch stopmaterial) may then be formed overlying the copper bond pads of the Mx-1interconnect layer 210, followed by a core plate 204 comprising aconductive ferromagnetic material layer (e.g., cobalt, nickel, tantalum,a TiN/Co/TiN stack, a TaN/Co stack, or another high-permeabilityferromagnetic core material). Each ferromagnetic core plate layer 204,in one example, is patterned to form slots or other spaced apart tracesin the conductive plate, which are mutually electrically conductive toeach other in order to avoid eddy current losses in the plate.

Isolation layers ILD 206 and TOP IMD 208 formed over the lower coreplate 204 and the etch stop layer 214, may comprise insulating ordielectric materials (e.g., TaN, SiO2, an etch-stop material, SiN, SiC,SiC:H, or another insulating material). Trenches are then formed withinthe isolation layers 206 and 208, wherein a diffusion barrier layer 216(e.g., TaN, TiN) and a conductive material layer 218 (e.g., copper,aluminum, tantalum, or a TaN/Al stack) is disposed within the trenchesto form the inductor coil 202. The structure may then receive a CMPoperation to further define the shape and turns of the inductor coil 202and to provide isolation spaces between the electrically conductiveturns of the inductor coil 202.

Thus, an inductor coil comprising a conductive material is disposed andformed within the trenches of the second isolation layer 208 overlyingthe first isolation layer 206 and the core plate 204. Optionally, asshown, the formation of the inductor structure L may be followed byanother deposition of an etch-stop material layer 220, a second or upperferromagnetic core plate 204, and one or more protective overcoatlayers, for example, protective overcoat layer PO 222, and protectiveovercoat layer PO2 224 (a third isolation layer) overlying the inductorcoil 202 and the core plate 204.

Vias, such as 212 comprising additional diffusion barrier layers 226 andconductive interconnects 228 may be formed within the protectiveovercoat layers PO 222, and PO2 224 to interconnect to the underlyingcircuit elements and structures. Bond pads 230 may be then formedoverlying the via structures or other openings for electrical connectionto one or more terminals 234 of the inductor 202. In the exemplarydevice 200 of FIGS. 2A and 2B, one terminal 234 a of the inductor coil202 connects to the Mx-1 copper layer 210 under the inductor L, and theother terminal 234 b connects to a bond pad 230 above inductor L.

FIG. 3A illustrates a top view of an exemplary integrated inductorstructure L having a two turn coil disposed within isolation layers of asemiconductor device 300 in accordance with another aspect of thepresent invention.

FIG. 3B is a cross-sectional side view taken along section line CC ofFIG. 3A, illustrating the exemplary integrated inductor structure L ofthe semiconductor device 300 of FIG. 3A. The inductor structure L ofdevice 300 of FIGS. 3A and 3B is similar to that of the inductor ofdevice 200 FIGS. 2A and 2B, and as such need not be fully describedagain for the sake of brevity except where noted. In the semiconductordevice 300, the inductor structure L comprises a two turn coil 302connected to a lower ferromagnetic material core plate 304 and having anupper core plate 304 disposed within the isolation layers, for example,within interlevel dielectric layer ILD 306 (a first isolation layer) andthe top inter-metal dielectric layer TOP IMD 308 (a second isolationlayer) of the semiconductor device 300.

The inductor structure L of device 300, for example, is formed above asemiconductor substrate in or above the copper metal interconnect layerssuch as a copper Mx-1 layer 310, wherein bond pads for the inductor Land an unrelated via structure 312 are shown. An etch-stop layer 314(e.g., TiN, Sic, SiC:N, or another etch stop material) may then beformed overlying the copper bond pads of the Mx-1 interconnect layer310, followed by a core plate 304 comprising a conductive ferromagneticmaterial layer (e.g., cobalt, nickel, tantalum, a TiN/Co/TiN stack, aTaN/Co stack, or another high-permeability ferromagnetic core material).Each ferromagnetic core plate layer 304, for example, is patterned toform slots or other spaced apart traces in the conductive plate, whichare mutually electrically conductive to each other in order to avoideddy current losses in the plate.

Isolation layers ILD 306 and TOP IMD 308 formed over the lower coreplate 304 and the etch stop layer 314, may comprise insulating materials(e.g., TaN, SiO2, an etch-stop material, SiN, SiC, SiC:H, or anotherinsulating material). Trenches are then formed within the isolationlayers 306 and 308, wherein a diffusion barrier layer 316 (e.g., TaN,TiN) and a conductive material layer 318 (e.g., copper, aluminum,tantalum, or a TaN/Al stack) is disposed within the trenches to form theinductor coil 302. In the present example, prior to the deposition ofthe diffusion barrier layer 316 and the conductive coil material layer318, an opening for an interconnect is patterned through to the lowercore plate 304 for connecting one end of the coil 302 to the lower coreplate 304. In this way a series L-C circuit may be provided, wherein thelower plate 304 serves both as a capacitor plate and as a core toincrease the inductance of the coil 302. Thereafter, the structure maythen receive a CMP operation to further define the inductor coil 302 andto provide isolation spaces between the electrically conductive turnsthereof.

Thus, an inductor coil comprising a conductive material is disposed andformed within the trenches of the second isolation layer 308 overlyingthe first isolation layer 306 and the core plate 304. Optionally, asshown, the formation of the inductor structure L may be followed byanother deposition of an etch-stop material layer 320, a second or upperferromagnetic core plate 304, and one or more protective overcoatlayers, for example, protective overcoat layer PO 322, and protectiveovercoat layer PO2 324 (a third isolation layer) overlying the inductorcoil 302 and the core plate 304.

Vias, such as 312 comprising additional diffusion barrier layers 326 andconductive interconnects 328 may be formed within the protectiveovercoat layers PO 322, and PO2 324 to interconnect to the underlyingcircuit elements and structures. Bond pads 330 may be then formedoverlying the via structures or other openings for electrical connectionto one or more terminals 334 of the inductor 302. In the exemplarydevice 300 of FIGS. 3A and 3B, one terminal 334 a of the inductor coil302 connects to the Mx-1 copper layer 310 under the inductor L, and theother terminal 334 b connects to a bond pad 330 above inductor L.

FIG. 4 illustrates an exploded isometric view of an exemplary embodimentof an improved single turn inductor device L 400 disposed between twoisolation layers disposed between two conductive ferromagnetic coreplates each core plate comprising a plurality of mutually electricallyconductive spaced apart traces in accordance with the present invention.The exemplary inductor device 400 of FIG. 4 is fabricated with astructure similar to that of the single turn inductor of device 100 ofFIGS. 1A and 1B, and as such need not be fully described again for thesake of brevity except where noted.

FIG. 4 illustrates additional details associated with the implementationof such integrated inductors, including various details of the singleand two core plate implementations illustrated in the two turn devices200 and 300 of FIGS. 2A, 2B, 3A, and 3B. Although the devicesillustrated herein have included one and two turn inductor coils, itwill be appreciated by those skilled in the art that inductor coilshaving any number of turns and having multiple layers of turns andmultiple core plates (e.g., planar or contoured layer type core plates,which will be described infra) is anticipated in the context of thepresent invention.

Inductor device L 400, for example, provides an inductor coil 402comprising one or more turns formed between one or more ferromagneticcore plates comprising a plurality of mutually electrically conductivespaced apart traces. As discussed, one or more of the core plates issuitable for use as a plate of a capacitor used in the integratedcircuit. The inventors of the present invention has appreciated thateven though the surface area of such “slotted” core plates and thecorresponding permeability may actually decrease to some extent, thequality factor Q of the inductor device may be improved. The inventorsrealized that the use of solid conductive plates or layers often causeseddy currents to develop in the solid relatively large open areasthereof and result in added power consumption or eddy current losses.

In addition to these improvements, the inventor has appreciated that theuse of these slotted plates have other peripheral benefits such asreduction of “dishing” during CMP processing relative to the use oflarger continuous or solid conductive areas. Although the trace and slotwidths have been illustrated as nearly equal for drawing purposes, thetrace to slot width ratios may be adjusted as needed, and for example,be on the order of around 2 microns, which advantageously providefiltering of relatively high frequency EMI noise.

Inductor device L 400 comprises a lower or first core plate layer 404, afirst isolation layer 406, a conductive layer 408 to form the inductorcoil 402, a second isolation layer 410, and an upper or second coreplate layer 412. The lower core plate layer 404 and upper core platelayer 412 comprise a conductive high-permeability ferromagneticmaterial, for example, cobalt that is sometimes used in the silicideprocess. Core plate layers 404 and 412 may further be formed as aplurality of conductive traces 424 and spaces or slots 426, wherein theplurality of traces 424 are mutually electrically conductive and spacedapart.

First isolation layer 406 and second isolation layer 410 (e.g., aninsulative material, OSG, FSG, TEOS, a low-k dielectric material, or anultra low-k dielectric material) provides isolation between the inductorcoil 402 formed in the conductive layer 408 and the lower (first) coreplate layer 404 or the upper (second) core plate layer 412. Conductivevias 428 formed in openings in the first isolation layer 406 and thesecond isolation layer 410 electrically connect between bond pads 430and end terminals 434 of the inductor coil 402.

The conductive layer 408, disposed within and between the isolationlayers 406 and 410, forms the inductor coil 402 of the inductor device L400. The conductive layer 408 comprises, for example, copper, aluminum,tantalum, or a TaN/Al stack. The inductor coil 402 of the conductivelayer 408 may be formed as one or more turns, and in one or more layersadequately spaced apart. In accordance with one aspect of the presentinvention, the traces 424 of first core plate layer 404 may, forexample, be aligned with traces 424 of second core plate layer 412, ormay be aligned orthogonal to each other.

Alternately, the upper isolation layer 410 may comprise an etch stoptype layer (e.g., SiN, a hard mask or another etch-stop material layer,an insulative material layer) disposed overlying the conductive layer408. Isolation layer 408 is generally designed as a relatively thinlayer to maximize the mutual coupling between the upper core plate 412and the inductor coil 402 and thus the inductance permeability.

Note, in the particular layout of the inductor L 400, a web 460 is usedacross the core plates 404 and 412 to electrically connect traces 424,such that they are mutually electrically conductive. Plate connections(not shown) may further be connected to the core plates 404 and 412 ofinductor L 400 for external capacitor plate connections, for example.

FIG. 5A illustrates a simplified top view of an exemplary integratedinductor structure L having a two turn coil disposed within isolationlayers of a semiconductor device 500 in accordance with another aspectof the present invention.

FIG. 5B is a cross-sectional side view taken along section line DD ofFIG. 5A, illustrating the exemplary integrated inductor structure L ofthe two turn coil and an overlying ferromagnetic material core platelayer disposed within a PO2 isolation layer of the semiconductor device500 of FIG. 5A. In the semiconductor device 500, the inductor structureL comprises the two turn coil 502 and an overlying ferromagneticmaterial core plate layer 504 disposed together in a second protectiveovercoat isolation layer PO2 524 of the semiconductor device of FIG. 5A.Some of the lower layers illustrated in the present invention aresimilar to those previously described, and so may not be fully describedagain for the sake of brevity except where noted.

As before, the device 500 of the present implementation of theinvention, for example, is formed above a semiconductor substrate abovethe copper metal interconnect layers such as a copper Mx-1 layer 510,wherein bond pads for the inductor L and an unrelated via structure 512are shown. An etch-stop layer 514 (e.g., TiN, Sic, SiC:N, or anotheretch stop material) may then be formed overlying the copper bond pads ofthe Mx-1 interconnect layer 510. Isolation layers ILD 506 and TOP IMD508 formed overlying the etch stop layer 514, may comprise insulating ordielectric materials (e.g., TaN, SiO2, an etch-stop material, SiN, SiC,SiC:H, or another insulating material).

Openings are then formed within the isolation layers 506 and 508,wherein a diffusion barrier layer 516 (e.g., TaN, TiN) and a conductivematerial layer 518 (e.g., copper, aluminum, or a TaN/Al stack) isdisposed to form conductive vias connecting to the underlying metalinterconnect layer 510. Another etch-stop material layer 520 maytypically follow the interconnect via formation.

A first protective overcoat layer PO 522 is then formed overlying theetch stop layer 520 and the vias of the conductive material layer 518.Openings within the protective overcoat layer PO 522 and etch stop layer520 are then provided wherein another conductive layer 528 (e.g.,aluminum, tantalum, or a TaN/Al stack) is disposed. Conductive layer 528is further patterned to form the inductor coil 502, while interconnectportions of conductive layer 528 are patterned to connect a bond pad 530to one of a pair of end terminals 534 of the inductor coil 502, and fromanother of the end terminals 534 to the underlying metal layers such asinterconnect layer 510.

In this implementation, an insulation layer (e.g., SiO₂) is thendisposed overlying the inductor coil 502 formed by the conductive layer528, followed by the core plate layer 504 comprising a conductiveferromagnetic material layer (e.g., cobalt, nickel, tantalum, aTiN/Co/TiN stack, a TaN/Co stack, or another high-permeabilityferromagnetic core material). Again, although not shown, theferromagnetic core plate layer 504 may be patterned similar to FIG. 4 toform slots or other spaced apart traces in the conductive plate 504,which are mutually electrically conductive to each other in order toavoid eddy current losses in the plate.

Optionally, as shown, the formation of the inductor structure L ofdevice 500 may be followed by another protective overcoat layer, forexample, protective overcoat layer PO2 524 (a third isolation layer)overlying the inductor coil 502 and the core plate layer 504. Thus, aninductor coil comprising a conductive material layer 528 (e.g., copper,aluminum, tantalum, or a TaN/Al stack) is disposed and formed togetheroverlying the first protective overcoat layer PO 522. Note that the coreplate 504 of the present implementation is essentially a contoured coreplate 504 overlying the inductor coil turns, thereby potentiallyproviding greater mutual coupling and a higher permeability to theinductor coil 502. Note that if the coil material 528 is copper, adiffusion barrier may be deposited prior to formation thereof, as may beappreciated.

FIG. 6A illustrates a simplified top view of an exemplary integratedinductor structure L having a two turn coil disposed within isolationlayers of a semiconductor device 600 in accordance with still anotheraspect of the present invention.

FIG. 6B illustrates a cross-sectional side view taken along section lineEE of FIG. 6A, of the exemplary integrated inductor structure L of thetwo turn coil overlying a ferromagnetic material core plate layerdisposed together within a trench in the PO and PO2 isolation layers ofthe semiconductor device 600 of FIG. 6A. The inductor structure L ofdevice 600 of FIGS. 6A and 6B is similar to that of the inductor ofdevice 500 FIGS. 5A and 5B, and as such need not be fully describedagain for the sake of brevity except where noted.

In particular, after the first protective overcoat layer PO 622 has beenformed overlying the etch stop layer 620 and the vias of the conductivematerial layer 618, trenches and openings within the protective overcoatlayer PO 622 and etch stop layer 620 are provided. Within these trenchesand openings a diffusion barrier layer 625 (e.g., TaN, TiN) and a coreplate layer 604 comprising a conductive ferromagnetic material layer(e.g., cobalt, nickel, tantalum, a TiN/Co/TiN stack, a TaN/Co stack, oranother high-permeability ferromagnetic core material) is disposed.

Another diffusion barrier layer 626 (e.g., TaN, TiN) followed by aconductive layer 628 is further disposed within the trenches and openingto form the inductor coil 602. As before, interconnect portions ofconductive layer 628 are patterned to connect a bond pad 630 to one of apair of end terminals 634 of the inductor coil 602, and from another ofthe end terminals 634 to the underlying metal layers such asinterconnect layer 610. The structure may then receive an etch and a CMPoperation to further define the shape and turns of the inductor coil 602and to provide isolation spaces 640 between the electrically conductiveturns of the inductor coil 602 as well as the core plate layer 604.

Note in this implementation, unlike that of FIG. 4, the ferromagneticcore plate layer 604 is patterned by the etch process to form a singleconductive core plate 604 along the length of the coil 602. In this way,a helical slot is formed along the length (and trace) of the core plate604, thereby avoiding eddy current losses in a larger solid plate.

Optionally, as shown, the formation of the inductor structure L ofdevice 600 may be followed by another protective overcoat layer, forexample, protective overcoat layer PO2 624 (a third isolation layer)overlying the inductor coil 602 and the core plate layer 604. Thus, aninductor coil comprising a conductive material layer 628 (e.g., copper,aluminum, tantalum, or a TaN/Al stack) is disposed and formed togetherwithin the protective overcoat layers PO 622 and PO2 624. Again, notethat the core plate 604 of the present implementation is essentially acontoured core plate 604 surrounding much of the inductor coil turns,thereby potentially providing greater mutual coupling and a higherpermeability to the inductor coil 602.

FIG. 7A illustrates a simplified top view of an exemplary integratedinductor structure L having a two turn coil disposed within isolationlayers of a semiconductor device 700 in accordance with yet anotheraspect of the present invention.

FIG. 7B illustrates a cross-sectional side view taken along section lineFF of FIG. 7A, of the exemplary integrated inductor structure L of thetwo turn coil overlying a ferromagnetic material core plate layerdisposed together within a trench in the TOP IMD isolation layer of thesemiconductor device 700 of FIG. 7A.

The inductor structure L of device 700 of FIGS. 7A and 7B is similar toportions of the inductor L of devices 500 of FIGS. 5A and 5B, and 600 ofFIGS. 6A and 6B, and as such need not be fully described again for thesake of brevity except where noted.

As before, the device 700 of the present implementation, for example, isformed above a semiconductor substrate above the copper metalinterconnect layers such as a copper Mx-1 layer 710, wherein bond padsfor the inductor L and an unrelated via structure 712 are shown. Anetch-stop layer 714 (e.g., TiN, Sic, SiC:N, or another etch stopmaterial) may then be formed overlying the copper bond pads of the Mx-1interconnect layer 710. Isolation layers ILD 706 and TOP IMD 708 formedoverlying the etch stop layer 714, may comprise insulating or dielectricmaterials (e.g., TaN, SiO2, an etch-stop material, SiN, SiC, SiC:H, oranother insulating material).

Openings are then formed within the isolation layer 706, while trenchesand openings are formed in isolation layer 708. Within these trenchesand openings a diffusion barrier layer 716 (e.g., TaN, TiN) and a coreplate layer 704 comprising a conductive ferromagnetic material layer(e.g., cobalt, nickel, tantalum, a TiN/Co/TiN stack, a TaN/Co stack, oranother high-permeability ferromagnetic core material) is disposed.

Another diffusion barrier layer 717 (e.g., TaN, TiN) and a conductivelayer 718 (e.g., copper, aluminum, or a TaN/Al stack) is furtherdisposed within the trenches and opening to form the inductor coil 702and to form conductive vias connecting to the underlying metalinterconnect layer 710. The structure may then receive an etch and a CMPoperation to further define the shape and turns of the inductor coil 702and to provide isolation spaces 740 between the electrically conductiveturns of the inductor coil 702 as well as the core plate layer 704.

Note in this implementation, like that of FIGS. 6A and 6B, theferromagnetic core plate layer 704 is patterned by the etch process toform a single conductive core plate 704 along the length of the coil702. In this way, a helical slot may be formed along the length (andtrace) of the core plate 704, thereby avoiding eddy current losses in alarger solid plate.

Another etch-stop material layer 720 is then formed overlying theinductor coil 702 and the interconnect vias. A first protective overcoatlayer PO 722 is then formed overlying the etch stop layer 720. Openingswithin the protective overcoat layer PO 722 and etch stop layer 720 arethen provided wherein another diffusion barrier layer 726 (e.g., TaN,TiN) and another conductive layer 728 (e.g., aluminum, tantalum, or aTaN/Al stack) is disposed. Interconnect portions of conductive layer 728are patterned to connect a bond pad 730 to one of a pair of endterminals 734 of the inductor coil 702, and from another of the endterminals 734 to the underlying metal layers such as interconnect layer710.

Optionally, as shown, the formation of the inductor structure L ofdevice 700 may be followed by another protective overcoat layer, forexample, protective overcoat layer PO2 724 (a third isolation layer).Thus, an inductor coil 702 comprising a conductive material layer 728(e.g., copper, aluminum, tantalum, or a TaN/Al stack) is disposed andformed together within trenches in the TOP IMD layer 708. Thus, theintegrated inductor L of the present invention provides more predictableinductor performance in a circuit, by mitigating eddy current losses,sufficiently shielding the device from noise, to limit power consumptionin modern high-speed, high-density devices.

In the above discussion, the inductance of the coil is increased by useof a core plate material residing above or below the coil. In anotheralternative aspect of the present invention, a core plate may beemployed on the same metallization layer as the coil and thus reside inthe same insulating layer. For example, the dielectric layer may bedeposited and patterned to form a first coil-shaped trench therein. Acoil metal deposition may then be employed to fill the coil-shapedtrench, followed by a planarization. A second set of vias or trenchesmay then be employed near the coil in a variety of differing patterns,as may be desired. A ferromagnetic material deposition is thenperformed, wherein the ferromagnetic material fills the second vias toform one or more core plates near the inductor coil for an improvementof the inductance thereof.

These and other aspects of the invention may be carried out inassociation with integrated inductor formation in any type ofinterconnect process, including but not limited to single and dualdamascene processes. However, it is noted at this point that theinvention is not limited to such specific applications, and further thatthe structures illustrated and described hereinafter are not necessarilydrawn to scale.

Although the invention has been illustrated and described with respectto one or more implementations, equivalent alterations and modificationswill occur to others skilled in the art upon the reading andunderstanding of this specification and the annexed drawings. Inparticular regard to the various functions performed by the abovedescribed components (assemblies, devices, circuits, systems, etc.), theterms (including a reference to a “means”) used to describe suchcomponents are intended to correspond, unless otherwise indicated, toany component which performs the specified function of the describedcomponent (e.g., that is functionally equivalent), even though notstructurally equivalent to the disclosed structure which performs thefunction in the herein illustrated exemplary implementations of theinvention. In addition, while a particular feature of the invention mayhave been disclosed with respect to only one of several implementations,such feature may be combined with one or more other features of theother implementations as may be desired and advantageous for any givenor particular application. Furthermore, to the extent that the terms“including”, “includes”, “having”, “has”, “with”, or variants thereofare used in either the detailed description and the claims, such termsare intended to be inclusive in a manner similar to the term“comprising.”

1. An inductor structure formed in an integrated circuit, comprising: afirst isolation layer; a first core plate comprising a plurality ofelectrically coupled conductive traces comprising a conductiveferromagnetic material layer disposed over an upper surface of the firstisolation layer; a second isolation layer overlying the first isolationlayer; and an inductor coil comprising a conductive material layerformed within the second isolation layer; wherein the first core plateincreases an inductance of the inductor coil.
 2. The inductor structureof claim 1, wherein the conductive ferromagnetic material comprises oneof cobalt, nickel, tantalum, a TiN/Co/TiN stack, a TaN/Co stack, and ahigh-permeability ferromagnetic core material.
 3. The inductor structureof claim 1, further comprising: a third isolation layer formed over theinductor coil conductive layer; and a second core plate comprising aplurality of electrically coupled conductive traces comprising aconductive ferromagnetic layer disposed over an upper surface of thethird isolation layer, thereby providing a ferromagnetic core plateabove and below the inductor coil.
 4. The inductor structure of claim 3,wherein the conductive material layer of the inductor coil comprises oneof copper, aluminum, tantalum, and a TaN/Al stack.
 5. The inductorstructure of claim 3, wherein at least one of the first and second coreplates of the inductor further comprises a plate of a capacitor.
 6. Theinductor structure of claim 5, wherein one of the first and second coreplates of the capacitor is electrically connected to the inductor coil.7. The inductor structure of claim 3, wherein the traces of the firstcore plate of the inductor are aligned orthogonal to the traces of thesecond core plate.
 8. The inductor structure of claim 1, wherein thematerial of at least one of the isolation layers comprises one of TaN,SiO2, an etch-stop material, SiN, SiC, SiC:H, and an insulative ordielectric material.
 9. The inductor structure of claim 1, wherein theinductor coil is formed completely within the metal layers of theintegrated circuit.
 10. The inductor structure of claim 1, wherein theinductor coil is formed in one or more protective overcoat layers of theintegrated circuit.
 11. The inductor structure of claim 1, wherein theisolation layers comprise one of OSG, FSG, TEOS, a low-k dielectricmaterial, and an ultra low-k dielectric material.
 12. A method offorming an integrated inductor structure over a semiconductor substrate,comprising: providing a first isolation layer disposed over thesemiconductor substrate; forming a first core plate comprising aplurality of electrically coupled conductive traces comprising aconductive ferromagnetic material layer disposed over an upper surfaceof the first isolation layer; forming a second isolation layer over thefirst isolation layer and the first core plate; and forming an inductorcoil comprising a conductive material layer disposed within trenches inthe second isolation layer; wherein the first core plate increases aninductance of the inductor coil.
 13. The method of claim 12, furthercomprising: forming a third isolation layer formed over the inductorcoil conductive layer; and forming a second core plate comprising aplurality of electrically coupled conductive traces comprising aconductive ferromagnetic layer disposed over an upper surface of thethird isolation layer, thereby providing a ferromagnetic core plateabove and below the inductor coil.
 14. The method of claim 13, whereinat least one of the first and second core plates of the inductor furthercomprises a plate of a capacitor.
 15. The method of claim 14, whereinthe plate of the capacitor is electrically connected to the inductorcoil.
 16. The method of claim 13, wherein the traces of the first coreplate of the inductor are aligned orthogonal to the traces of the secondcore plate.
 17. The method of claim 12, wherein the inductor coil isformed completely within the metal layers of the integrated circuit. 18.The method of claim 12, wherein the inductor coil is formed in one ormore protective overcoat layers of the integrated circuit.
 19. A methodof forming an integrated inductor structure over a semiconductorsubstrate, comprising: providing a first isolation layer disposed overthe semiconductor substrate; forming trenches within the first isolationlayer; forming a core plate comprising a conductive ferromagneticmaterial layer disposed within the trenches of the first isolationlayer; forming a second isolation layer over the core plate and thefirst isolation layer; forming an inductor coil of a conductive materiallayer disposed within trenches overlying the second isolation layer andthe core plate; and removing a portion of the inductor coil material andthe first core plate material to provide isolation between turns of theinductor coil and to define an electrically continuous core plate withradially spaced apart traces; wherein the core plate increases aninductance of the inductor coil.
 20. The method of claim 19, wherein thecore plate of the inductor further comprises a capacitor plate, andwherein the plate of the capacitor is electrically connected to theinductor coil.
 21. An inductor structure formed in an integratedcircuit, comprising: a first isolation layer; a coil-shaped trenchformed in the first insulation layer; a core plate layer comprising aconductive ferromagnetic material residing in the coil-shaped trench; aconductive layer overlying or underlying the core plate layer in thecoil-shaped trench, thereby forming an inductor coil, wherein the coreplate layer increases an inductance of the inductor coil.
 22. Aninductor structure formed in an integrated circuit, comprising: a firstisolation layer; a coil-shaped trench formed in the first insulationlayer; one or more core plate vias or trenches formed in the firstinsulation layer and electrically isolated from the coil-shaped trench;a conductive material residing in the coil-shaped trench and forming aninductor coil therein; and a conductive ferromagnetic material residingin the one or more core plate vias or trenches, wherein the conductiveferromagnetic material forms one or more core plates that increase aninductance of the inductor coil.